In step 3, using repeated measures analysis of variance, the changes in vitamin D will be described separately for each ethnic group within each of the supplemented groups. This will depict separately for each ethnic group the changes in vitamin D over time as a function of the level of supplementation. This method will reveal how soon after supplementation the changes in blood (from baseline) are detected, the linear change in blood vitamin D over time and, when and if a peak level (or plateau) was attained. Adjusted differences will be examined by use of multiple regression with and without the inclusion of other covariates. Regression coefficients provide the formula for the linear association between vitamin D in blood and time, separately for each ethnic group. In the event that there is a non-linear change over time, appropriate data transformations will occur as necessary. This step also will provide information on the magnitude of importance that covariates play in changes in vitamin D over time within each ethnic group. As an example, we may find that seasonality plays a significant role in changes in vitamin D for Caucasian women but the association is not as strong for African American women. Further, these associations may become similarly unimportant at the higher levels of supplementation.